We provide cochlear implants (CIs) to young children who are deaf to alter their developmental course[unreadable] with regard to listening, speaking, learning, and socializing. The intended ultimate result in for the child to[unreadable] grow into a competent member of the hearing society. The brief history of developmental Cl research has[unreadable] shown that pediatric Cl users achieve substantial benefits in most of these areas. One set of studies[unreadable] proposed in this project aims to continue evaluating the outcomes of current and emerging practices of[unreadable] cochlear implantation. Our interests in current practices focus on whether the initial advantages of[unreadable] implantation early in life persist into the implant users' middle-school years. We will also focus on whether[unreadable] young adults implanted in childhood attain many of the social, occupational, and personal outcomes found[unreadable] among hearing individuals. Furthermore, we will examine whether some of these individuals identify with the[unreadable] Deaf community exclusively or with the hearing community as well. Within these studies, we will also[unreadable] examine the benefits of new practices in cochlear implantation. Specifically, we will examine whether[unreadable] bilateral implantation in infancy provides benefits to listening, speech, and language learning. Finally, we will[unreadable] evaluate if implantation before 12 months of age provides additional advantages to speech, language, and[unreadable] listening development compared to implantation after 12 months of age.[unreadable] A second set of studies shift away from outcome studies. These studies are concerned with advancing[unreadable] our understanding of the basic perceptual and cognitive systems that influence (and emerge) from a child's[unreadable] experiences with her Cl. The auditory experiences of the deaf child who receives a Cl appear to be[unreadable] superficially sufficient for the development of functional speech perception and spoken language. However,[unreadable] these children have qualitatively different auditory abilities and experiences that are likely to result in[unreadable] important differences in their development of speech perception. These children's abilities to perceive and[unreadable] employ properties of the speech signal subsequently bootstrap their language learning, and the development[unreadable] of memory systems involving phonological short-term and long-term memory that are important in language[unreadable] learning. A series of studies will examine how well infant Cl users develop preferences for properties of[unreadable] speech that have been shown to be salient to hearing infants. The manner in which phonemic categories are[unreadable] formed and subphonemic cues are used in perception will also be examined in these children. Finally, a[unreadable] model of the relationships between speech perception, short-term phonological memory, long-term[unreadable] phonological procedural memory, and declarative memory and early word learning will be examined in these[unreadable] children. These data will be later used to predict longer-term vocabulary development.